1. Field of the Invention
The present invention relates to a navigation system for guiding a driver to a destination via a predetermined route and, more particularly, to a navigation system having a function to set point data by inputting the absolute coordinates by manual input or by input through data communication.
2. Related Art
A conventional navigation system guides the driver along a route so that he or she can visit a first destination safely by car. In recent years, technology improving performance with regard to precision, operability and visibility of navigation has been vigorously developed, and a variety of systems have been proposed. Typically, a navigation system is equipped with a display screen to be used for setting the route and a display screen to be opened automatically or in response to a demand of the driver for guidance along the route. The display screen, after the start of guidance, provides a section diagram covering a wide range of several Sections including a plurality of sections showing the route, including the section in which the automobile is running, and an intersection diagram for guiding the driver at road intersections.
Some navigation systems provide information such as the remaining distance, intersection name and right or left turn to be made at the intersection, in order to follow the correct route. These systems provide information by which the driver can confirm the route in his or her course and further provide, not only a display, but also audio guidance.
In the conventional navigation system, the starting point and the destination have to be input so as to set the route. When the starting point and the destination are determined by this input, the route is searched for from the neighborhoods of the starting point and the destination and the road information data in between so that the optimum route is selected from a plurality of routes. For example, there have been proposed: a system in which the target position such as the starting point or the destination is classified according to sight-seeing, parking zone or restaurant and is coded according to the area such as the prefecture or city so that the data is input in the form of codes; a system in which menus are displayed so that they may be sequentially selectively input; a system in which node data are connected to define a road network including previously stored position information in terms of the east longitude and north latitude coordinates; and a system in which the telephone number is input.
A telephone number inputting system is exemplified by that disclosed in Japanese Patent Laid-Open No. 187898/1990, and a classification or code number inputting system is exemplified by that disclosed in Japanese Patent Laid-Open No. 173820/1989. In Japanese Patent Laid-Open No. 1738223/1989, on the other hand, there is disclosed a system in which a destination is set in terms of code numbers which correspond to previously stored coordinate data for destinations as the destination information.
However, the destination inputting system of the prior art cannot always set the destination the driver desires to reach. In case, for example, the destination is to be set at the house of a friend, the telephone number of the friend has to be registered in the navigation data according to the telephone number inputting system. However, it frequently occurs that the telephone number of the friend's house is not registered. Thus, the map displayed shows, as a representative point, the area covering the friend's house where the local office number coincides. The natural result is that the displayed map covers such a wide area as to make it difficult to identify the location of the friend's house. To overcome this difficulty, it is sufficient to register the telephone number of the friend's house, but the amount of data increases so much that the cost becomes extremely high.
On the other hand, a code number inputting system can set the destination precisely. In order to allow the user to set a number of unspecified destinations such as a friend's home, however, the unspecified destinations must be coded one by one. When the data codes are input they must be converted into point information. Then, there arises a problem that the user has to pay the costs for the encoding process and for the device for storing the data.